1. Field of the Invention
The present invention relates to a tool and a tool holder to be used in a machine tool. More particularly, the present invention relates to a tool and tool holder removably attachable to the spindle of a machine tool.
2. Description of the Related Art
In a machine tool provided with a spindle such as machining center, the maximum rotational speed of the spindle is determined by the structure of a bearing rotatably supporting the spindle and a lubrication system of this bearing. For this reason, when it is necessary to rotate a tool at a higher rotational speed than the maximum rotational speed of the spindle, an accelerating apparatus is used.
As the accelerating apparatus, for example, an accelerating apparatus provided with a gear mechanism such as an epicyclic gearing which holds the tool and is removably attachable to the spindle is well known.
However, when raising the rotational speed of the tool to a higher speed than the maximum rotational speed of the spindle by the above gear mechanism, the accelerating apparatus increasingly generates heat at a super high rotational speed such as tens of thousands to hundreds of thousands of revolutions per minute, so the machining tolerance of a workpiece can be influenced by the heat. Further, at the above super high rotational speed, the noise from the accelerating apparatus can also increase. Furthermore, a highly reliable precision structure able to withstand the above super high rotational speed is required for the accelerating apparatus, so there is the disadvantage that the manufacturing cost becomes relatively high.
An object of the present invention is to provide a tool and a tool holder capable of changing the rotational speed of a machining tool for machining a workpiece independently from the rotational speed of a spindle of a machine tool.
Another object of the present invention is to provide a machine tool provided with the above tool and tool holder.
Still another object of the present invention is to provide a method of driving the above tool.
Still another object of the present invention is to provide a tool management system for managing the above tool.
According to a first aspect of the present invention, there is provided a tool attachable to a spindle of a machine tool comprising a machining tool for machining a workpiece; an electric motor for driving the machining tool; and a generator for generating electric power to drive the electric motor by the rotation of the spindle.
According to a second aspect of the present invention, there is provided a tool attachable to a spindle of a machine tool comprising a machining tool for machining a workpiece; an electric motor for driving the machining tool; a generator for generating electric power to drive the electric motor by the rotation of the spindle; and a control means for controlling a supply of electric power generated by the generator to drive and control the machining tool.
According to a third aspect of the present invention, there is provided a tool attachable to a spindle of a machine tool comprising a machining tool for machining a workpiece; an electric motor for driving the machining tool; a generator for generating electric power to drive the electric motor by the rotation of the spindle; an electric power receiving part other than the electric motor for receiving supply of the electric power; a secondary battery able to supply power to the electric power receiving part; and a charging circuit for charging the secondary battery with part of the electric power generated by the generator.
According to a fourth aspect of the present invention, there is provided a tool attachable to a spindle of a machine tool comprising a machining tool for machining a workpiece; an electric motor for driving the machining tool; a generator for generating electric power to drive the electric motor by the rotation of the spindle; a processing circuit for processing data related to machining of the workpiece by the machining tool; and a transmitting and receiving circuit for performing at least one of transmission and reception of a wireless signal indicating information related to machining of a workpiece by the machining tool.
According to a fifth aspect of the present invention, there is provided a tool holder attachable to a spindle of a machine tool for rotatably holding a machining tool for machining a workpiece, the tool holder comprising an electric motor for driving the machining tool and a generator for generating electric power to drive the electric motor by the rotation of the spindle.
According to a sixth aspect of the present invention, there is provided a machine tool comprising a machine tool body provided with a spindle, a driving means for driving the spindle, and at least one control axis for changing a relative position between the spindle and a workpiece; a control apparatus for controlling the driving means and the control axis in accordance with a machining program; and a tool attachable to the spindle and provided with a machining tool for machining a workpiece, an electric motor for driving the machining tool, and a generator for generating electric power to drive the electric motor by the rotation of the spindle.
According to a seventh aspect of the present invention, there is provided a method of driving a tool attachable to a spindle of a machine tool, the tool being provided with a machining tool for machining a workpiece, an electric motor for driving the machining tool, and a generator for generating electric power to drive the electric motor by the rotation of the spindle, comprising the steps of generating alternating current having a frequency in accordance with the rotational speed of the spindle; driving the electric motor by the generated alternating current; and controlling the rotational speed of the machining tool in accordance with the frequency of the alternating current.
According to an eighth aspect of the present invention, there is provided a tool management system comprising a tool attachable to a spindle of a machine tool, the tool comprising a machining tool for machining a workpiece, an electric motor for driving the machining tool, a generator for generating electric power to drive the electric motor by the rotation of the spindle, a processing circuit for processing data related to machining of the workpiece by the machining tool; a transmitting and receiving circuit for performing at least one of transmission and reception of a wireless signal indicating information related to machining of a workpiece by the machining tool; and a management apparatus for performing at least one of reception of data from the transmitting and receiving circuit and transmission of data to the receiving circuit and managing the data.